WEDNESDAY, March 12 (HealthDay News) — A new survey reports that teenagers spend far too many hours a week in front of TVs and computers, and those in poor neighborhoods have even more "screen time."

"The take-home message is that we have to find out why some of these kids don't have healthier alternatives in their neighborhoods," said study author Tracie A. Barnett, a researcher at Sainte-Justine Children's Hospital Research Center in Montreal.

While it's possible that kids spend their time at home watching television documentaries and perusing classic novels on their computers, researchers assume that they're not exercising their brains or their bodies. Some studies have suggested a link between TV watching and obesity in children, Barnett noted.

In fact, a study published earlier this month reported that cutting TV and computer time in half helped younger children eat less and lose weight.

To figure out what teenagers were up to, Barnett and her colleagues surveyed 1,293 seventh-grade students from 10 Montreal high schools in 1999 and followed many of them for five years.

The students reported the number of hours they spent watching TV, playing video games, or using computers. The findings were expected to be released Wednesday at the American Heart Associations Annual Conference on Cardiovascular Disease Epidemiology and Prevention, in Colorado Springs, Colo.

Half of the boys and a quarter of the girls reported spending an average of more than 42 hours a week in front of electronic screens. TV was the most common form of screen use, accounting for 85 percent of the time.

Girls who lived in the poorest neighborhoods were five times more likely to spend the most time in front of screens than those in the richest neighborhoods.

The girls in poor neighborhoods "might be more vulnerable to perceptions that their neighborhoods are not safe," Barnett suggested. "It's possible that the boys are a little less affected, and they go out anyway."

Future research will try to determine why there's a link between poverty and time spent in front of screens, Barnett said.

Frederick Zimmerman, an associate professor of health services at the University of Washington and Seattle Children's Hospital Research Institute, said parents in poor neighborhoods face tough choices when they decide whether to send their kids outside, where it might be dangerous, or let them sit in front of electronic screens inside.

"Parents — particularly those in low-income neighborhoods — face an agonizing choice between the dangers outside the home and those emanating from the TV screen or computer monitor," Zimmerman said. "Sometimes, it is tempting to believe that the dangers posed by extensive TV or computer use are not real, but they are," he said. "Numerous studies have documented the associations between excessive TV viewing and obesity, smoking, alcohol use, violent and aggressive behavior, tolerance of aggression against women, and poor school performance."